Bioinspired coupled helical coils for soft tissue engineering of tubular structures - Improved mechanical behavior of tubular collagen type I templates.

The design of constructs for tubular tissue engineering is challenging. Most biomaterials need to be reinforced with supporting structures such as knittings, meshes or electrospun material to comply with the mechanical demands of native tissues. In this study, coupled helical coils (CHCs) were manufactured to mimic collagen fiber orientation as found in nature. Monofilaments of different commercially available biodegradable polymers were wound and subsequently fused, resulting in right-handed and left-handed polymer helices fused together in joints where the filaments cross. CHCs of different polymer composition were tested to determine the tensile strength, strain recovery, hysteresis, compressive strength and degradation of CHCs of different composition. Subsequently, seamless and stable hybrid constructs consisting of PDSII® USP 2-0 CHCs embedded in porous collagen type I were produced. Compared to collagen alone, this hybrid showed superior strain recovery (93.5±0.9% vs 71.1±12.6% in longitudinal direction; 87.1±6.6% vs 57.2±4.6% in circumferential direction) and hysteresis (18.9±2.7% vs 51.1±12.0% in longitudinal direction; 11.5±4.6% vs 46.3±6.3% in circumferential direction). Furthermore, this hybrid construct showed an improved Young's modulus in both longitudinal (0.5±0.1MPavs 0.2±0.1MPa; 2.5-fold) and circumferential (1.65±0.07MPavs (2.9±0.3)×10-2MPa; 57-fold) direction, respectively, compared to templates created from collagen alone. Moreover, hybrid template characteristics could be modified by changing the CHC composition and CHCs were produced showing a mechanical behavior similar to the native ureter. CHC-enforced templates, which are easily tunable to meet different demands may be promising for tubular tissue engineering. STATEMENT OF SIGNIFICANCE: Most tubular constructs lack sufficient strength and tunability to comply with the mechanical demands of native tissues. Therefore, we embedded coupled helical coils (CHCs) produced from biodegradable polymers - to mimic collagen fiber orientation as found in nature - in collagen type I sponges. We show that the mechanical behavior of CHCs is very similar to native tissue and strengths structurally weak tubular constructs. The production procedure is relatively easy, reproducible and mechanical features can be controlled to meet different mechanical demands. This is promising in template manufacture, hence offering new opportunities in tissue engineering of tubular organs and preventing graft failure.

Needs of children with a chronic bladder in preparation for transfer to adult care.

OBJECTIVE: Transfers to adult care can be problematic, resulting in postponement due to the protective nature of pediatric care and patient dependency. It is unknown whether these findings apply specifically to urology patients. Our department is taking part in a national general transition project. In this light, our aim was to investigate the specific needs of adolescent urologic patients, regarding their independence and transition. PATIENTS AND METHODS: 80 patients, born in 1975-1998, with a chronic bladder condition received a questionnaire. They were divided into pre- and post-transfer groups. Parents (n = 7) of post-transfer patients formed a third group. Questionnaires were based on those used in the national transition study, supplemented with urological questions. Pre-transfer patients were asked about their level of independence, what subjects were discussed during consultations, and their expectations and wishes regarding transfer. Post-transfer patients and parents were asked for their opinions on the transfer process. RESULTS: 73% (n = 58) responded (55 pre-transfer and 3 post-transfer patients plus parents). It appeared that the confidence built-up with the pediatric urologist impeded the transfer. An adequate level of disease-related knowledge was reported. Relationships, sexuality and fertility were hardly talked about (respectively n = 17, 16 and 18). Parents played an important role, which patients appreciated, confirming their dependency. Despite the 49% (n = 27) who stated they can arrange their urological care themselves, 44% (n = 24) felt ill-prepared for transfer. CONCLUSION: Although overall self-perceived knowledge is sufficient, the trust in and personal relationship with the pediatric urologist formed the greatest obstruction to successful transition. These findings have been used to improve support during transition by creating a transition protocol.

Aetiology of hypospadias: a systematic review of genes and environment.

BACKGROUND: Hypospadias is a common congenital malformation of the male external genitalia. Most cases have an unknown aetiology, which is probably a mix of monogenic and multifactorial forms, implicating both genes and environmental factors. This review summarizes current knowledge about the aetiology of hypospadias. METHODS: Pubmed was used to identify studies on hypospadias aetiology published between January 1995 and February 2011. Reference lists of the selected manuscripts were also searched to identify additional studies, including those published before 1995. RESULTS: The search provided 922 articles and 169 articles were selected for this review. Studies screening groups of patients with hypospadias for single gene defects found mutations in WT1, SF1, BMP4, BMP7, HOXA4, HOXB6, FGF8, FGFR2, AR, HSD3B2, SRD5A2, ATF3, MAMLD1, MID1 and BNC2. However, most investigators are convinced that single mutations do not cause the majority of isolated hypospadias cases. Indeed, associations were found with polymorphisms in FGF8, FGFR2, AR, HSD17B3, SRD5A2, ESR1, ESR2, ATF3, MAMLD1, DGKK, MID1, CYP1A1, GSTM1 and GSTT1. In addition, gene expression studies indentified CTGF, CYR61 and EGF as candidate genes. Environmental factors consistently implicated in hypospadias are low birthweight, maternal hypertension and pre-eclampsia, suggesting that placental insufficiency may play an important role in hypospadias aetiology. Exogenous endocrine-disrupting chemicals have the potential to induce hypospadias but it is unclear whether human exposure is high enough to exert this effect. Other environmental factors have also been associated with hypospadias but, for most, the results are inconsistent. CONCLUSIONS: Although a number of contributors to the aetiology of hypospadias have been identified, the majority of risk factors remain unknown.

Urological anomalies in anorectal malformations in The Netherlands: effects of screening all patients on long-term outcome.

INTRODUCTION: Urological anomalies are frequently seen in patients with anorectal malformations (ARM) and can result in upper urinary tract deterioration. Whether the current method of screening is valid, adequate and needed for all patients is not clear. We, therefore, evaluated the urological screening methods in our ARM patients for changes in urological treatment, outcome and follow-up. METHODS: The medical records of 331 children born with an ARM in the period 1983-2003 were retrospectively studied. Documentation of diagnosis, screening method, urological anomalies, treatment, complications, follow-up and outcome were measured. RESULTS: The overall incidence of urological anomalies was 52%. The incidence of urological anomalies and urological follow-up time decreased with diminishing complexity of the ARM. Hydronephrosis, vesico-urethral reflux, lower urinary tract dysfunction and urinary incontinence were encountered most. Treatment invasiveness increased with the increase of complexity of an ARM. Lower urinary tract dysfunction needing urological care occurred in 43% in combination with lumbosacral or spinal cord anomalies and in 8% with no abnormalities in the lumbosacral-/spinal region. CONCLUSIONS: Urological anomalies in patients with complex ARM are more severe than in patients with less complex ARM. Ultrasonography of the urinary tract should be performed in all patients. Voiding cysto-urethrography can be reserved for patients with dilated upper urinary tracts, urinary tract infections or lumbosacral and spinal abnormalities. All patients with complex ARM need urodynamic investigations. When using these indications, the screening for urological anomalies in ARM patients can be optimized with long-term follow-up in selected patients.

Urotherapy in children: quantitative measurements of daytime urinary incontinence before and after treatment according to the new definitions of the International Children's Continence Society.

OBJECTIVE: To assess the effectiveness of urotherapy in children with lower urinary tract dysfunction, according to the new definitions of the International Children's Continence Society. MATERIAL AND METHODS: We performed a retrospective review of 122 children (aged 8.8 ± 2.0 years) treated in an outpatient program for lower urinary tract dysfunction. Exclusion criteria included all neurologic abnormalities. In 98 children (80%) daytime urinary incontinence was a predominant symptom. Therapy consisted of an individually adapted drinking and voiding schedule, pelvic floor relaxation, instructions on toilet behavior, biofeedback uroflowmetry and if necessary recommendations for regulation of defecation. Before and at the end of training, patients were evaluated for number and severity of daytime wet accidents per week, using a scoring system to grade the severity of incontinence. Secondary measurements of accompanying voiding symptoms were performed. RESULTS: Of the 90 children with daytime urinary incontinence for whom sufficient objective data were collected, 42% became completely dry during the daytime and 36% showed a 50% or greater level of response. Secondary measurements showed a significant reduction in daily voiding frequency (mean 7.0 ± .3, P<0.0001) and mean post-void residual (P<0.003), and an improvement in flow pattern (P<0.05). CONCLUSIONS: Urotherapy is successful for the treatment of daytime urinary incontinence in children. Additional benefit was evident in improvement of accompanying voiding symptoms. A combination of the definitions of the International Children's Continence Society and a scoring system to grade severity improved the evaluation method. Further research into long-term efficacy will be performed.

[The undescended testis: arguments in favour of early treatment, provided retractile testis and acquired non-scrotal testis have been excluded]. / De niet-scrotale testis: argumenten vóór vroeg behandelen, mits retractiele testis en verworven niet-scrotale testis zijn uitgesloten.

--Guidelines for the treatment ofundescended testis (UDT) are sparse. Often an operation in the second year of life is advised. --Recent data indicate that the normal maturation process, which will ultimately lead to a normal quantity and quality of germ cells, is impaired as early as in the first half year of a newborn's life. None of the guidelines take this into account. Spontaneous descent after the fourth month following birth, of testes that have previously not descended, hardly ever occurs. --No differences have been shown in complication numbers between surgery before and after the first birthday. Orchidopexy prior to the 13th birthday reduces the risk of testicular cancer. --Therefore, based on these data, it is advised to perform orchidopexy in the second half of the first year of a newborn's life. In older boys a UDT must be treated before the 13th birthday. --In the Netherlands a lot more orchidopexies are done despite what may be expected based on prevalence numbers of UDT: testes retaining a normal volume that would most probably have descended spontaneously come puberty. --It remains important to carry out a careful physical examination and document the position of the testes soon after birth, and later on if UDT is suspected, to avoid unnecessary operations on retractile testes and acquired UDT.

Delayed intrauterine repair of an experimental spina bifida with a collagen biomatrix.

BACKGROUND/PURPOSE: The aim of the study was to evaluate whether a collagen biomatrix is useful for delayed intrauterine coverage of a surgically created spina bifida in a fetal lamb. METHODS: In 20 fetal lambs, surgery was performed at 72 or 79 days' gestation. In 15 lambs a spina bifida was created surgically. In 8 lambs it was covered with a collagen biomatrix 2 weeks later and in 7 lambs it was left uncovered. Five lambs served as sham operated controls. Neurological examination was performed at 1 week of age and afterwards the lambs were sacrificed for further histological evaluation. RESULTS: None of the 5 surviving lambs with the defect covered showed loss of spinal function and the architecture of the spinal cord was preserved in 4 of the 5 lambs. In the uncovered group, 1 of the 4 surviving lambs had loss of spinal function, 5 lambs were available for histological evaluation and 4 of them showed disturbance of the architecture of the spinal cord. CONCLUSIONS: Collagen biomatrices can be used for intrauterine coverage of an experimental spina bifida and can preserve the architecture of the spinal cord. Neurological outcome is not different between fetuses with their spinal cord covered and fetuses with uncovered cords.

Histological evaluation of acute covering of an experimental neural tube defect with biomatrices in fetal sheep.

OBJECTIVE: The aim of the study was to determine the histological effect on the neural tissue of in utero covering of an experimental neural tube defect in fetal lambs, with the use of two different biomatrices. MATERIALS AND METHODS: In 23 fetal sheep, surgery was performed at 79 days' gestation. In 19 of these, a neural tube defect was created, while 4 fetuses served as sham-operated controls. In 7 of the 19 operated fetuses the defect was left uncovered. In the remaining 12 animals the defect was covered either with a collagen biomatrix (4 animals), skin (3 animals), or small intestinal submucosa biomatrix (5 animals). The lambs were sacrificed at 1 week of age and histological examination was performed. RESULTS: All lambs with an uncovered neural tube defect showed histological damage of the spinal cord. In lambs in which the neural tube defect was covered, one half showed a normal architecture of the spinal cord while minor histological damage was present in the other half. Between the three groups in which the defect was covered, the histological outcome was comparable. CONCLUSIONS: Acute covering of an experimental neural tube defect in fetal lambs prevents severe histological damage to the spinal cord independent of the two biomatrices used in this study.

Hypospadias: a transgenerational effect of diethylstilbestrol?

BACKGROUND: In 2002, an increased risk of hypospadias was reported for sons of women exposed to diethylstilbestrol (DES) in utero, suggesting transgenerational effects of DES. The aim of this study was to further assess the association between parental DES exposure and hypospadias in a case-referent study. METHODS: Cases with hypospadias were retrieved from the hospital information system. Referents were recruited via the parents of cases. Both parents completed postal questionnaires. Associations were estimated by odds ratios (OR) with 95% confidence intervals (CI). Additionally, conditional logistic regression analyses were performed for a matched subset of parents. RESULTS: The final database included 583 cases and 251 referents. In the initial analyses, an indication was found for an increased risk of hypospadias when mothers were exposed to DES in utero: OR=2.3 (95% CI 0.7-7.9). Conditional logistic regression resulted in a stronger risk estimate: OR=4.9 (95% CI 1.1-22.3). Paternal exposure to DES did not increase the risk. CONCLUSIONS: The results confirm an increased risk of hypospadias when mothers were exposed to DES in utero. However, the excess risk appears to be of much smaller magnitude than in the 2002 study. Further research on the potential health risks for the third generation is of great importance.

In utero repair of an experimental neural tube defect in a chronic sheep model using biomatrices.

OBJECTIVE: Persistent exposure of the unprotected spinal cord to amniotic fluid and the uterine wall can lead to progressive damage of neural tissue in case of a myelomeningocele (two-hit hypothesis). The aim of this study was to evaluate whether in utero repair of an experimental neural tube defect in a fetal lamb could protect neural tissue from secondary injury and save neurologic functions after birth. METHODS: In 19 fetal lambs, a neural tube defect was created at 79 days' gestation. In 12 lambs the defect was covered either with a novel, molecular defined collagen-based biocompatible and biodegradable matrix (UMC) or with a small intestinal submucosa (SIS) biomatrix (Cook) or by closing the skin over the defect. RESULTS: All lambs with the defect covered showed no or minor neurologic morbidity in contrast to the lambs with the defect uncovered in which major neurologic morbidity was seen. CONCLUSIONS: These results demonstrate that long-term exposure of the open spinal cord to the intrauterine environment can lead to damage of neural tissue and, consequently loss of neurologic functions and that coverage of the defect can lead to a better neurologic outcome. Furthermore, we could show that a UMC biomatrix and an SIS biomatrix are useful for in utero coverage of a surgically created neural tube defect in our model.

Renal transplant nephrectomy in children: can an aggressive approach be recommended?

BACKGROUND: A patient with a failed renal graft is generally approached conservatively, especially when graft failure occurs more than 1 month after transplantation. This approach was the cause of extensive morbidity in our institution and therefore we evaluated the correctness of our approach towards transplanted children. PATIENTS AND METHODS: Case histories of 182 renal transplants in 145 patients, performed between 1977 and 1999 were reviewed. RESULTS: A total of 63 renal grafts failed: 19 between 0-1 month (group 1), 22 between 1 month and 1 yr (group 2) and 22 later than 1 yr after transplantation (group 3). Fifty-three grafts (84%) were removed: 100% of group 1, 86% of group 2 and 68% of group 3. The symptoms that indicated the need for graft removal were fever without a clear infection focus (n = 12), abdominal pain in the transplant area (n = 14), macroscopic hematuria (n = 10) and severe hypertension (n = 22). After transplant nephrectomy pain, fever and macroscopic hematuria completely resolved in all and hypertension resolved in 36% of patients. Transplant nephrectomy-associated morbidity was observed in 38% of the patients with 100% recovery. CONCLUSION: The clinical outcome confirmed the indications for transplant nephrectomy. Our future approach will be more aggressive: as soon as symptoms such as unexplained fever, local pain or macroscopic hematuria appear, graft removal will be performed without delay.

A rabbit model to tissue engineer the bladder.

A rabbit model was used for the evaluation of a collagen-based biomatrix of small intestinal submucosa (SIS, COOK) in comparison to a biochemically reconstructed biomatrix for bladder tissue regeneration. Rabbits underwent partial cystectomy and cystoplasty with SIS patch graft or with a biochemically defined collagen biomatrix. The grafts of the regenerated bladder wall were harvested at different intervals and tissue regeneration was evaluated. The results of the SIS and biochemically defined biomatrix grafts were comparable. At harvesting, we found five bladder stones and encrustation of the biomatrix in 21/56 animals. No stone formation was observed in the control group. The results of the molecularly defined biomatrix are thus far comparable to SIS. Both matrices show good epithelialization and ingrowth of smooth muscle cells. Both biomatrices show considerable encrustation, which appears to disappear in time. The rabbit model is suitable for bladder tissue engineering studies as it is an easy model to use. In this model, besides tissue regeneration, also some of the clinical problems are seen such as encrustation of foreign body material in the bladder. These aspects are subject for further pre-clinical studies in this animal model.

Anionic and cationic drug secretion in the isolated perfused rat kidney after neonatal surgical induction of ureteric obstruction.

OBJECTIVE: To study the pathophysiological changes of renal tubular drug transport mechanisms in congenital renal obstruction, by developing a model for perfusing the isolated kidney (IPK) after neonatal surgical induction of partial ureteric obstruction in Hanover Wistar rats. MATERIAL AND METHODS: Moderately severe obstruction of the right kidney of male rats was created by burying a segment of the right ureter under the psoas fascia at 5-7 days after birth. Different fluorescent substrates for renal organic anion and cation drug transport systems were added to the IPK, and the concentration of these substances with time analysed in perfusate and urine. RESULTS: The reproducibility in all groups of the glomerular filtration rate (GFR) and drug excretion was remarkably good. GFR was significantly lower in obstructed kidneys than in unobstructed kidneys. 123Rhodamine, a marker for organic cation and P-glycoprotein transport, had a significantly lower maximum excretion rate in the obstructed than in unobstructed kidneys. Renal fractional clearance (123rhodamine clearance corrected for diminished GFR) was also significantly lower in obstructed kidneys. There was no significant difference in maximum excretion (absolute and corrected GFR) for Lucifer Yellow, a marker for sodium-dependent organic anion transport. The maximum excretion rate of calcein, a marker for sodium-independent organic anion transport, was significantly lower in the obstructed than in the unobstructed kidneys, but significantly higher after correcting for reduced GFR. CONCLUSION: The IPK is a good model for studying the effect of neonatal renal obstruction on tubular drug transport. These results show that organic anion and cation transport mechanisms are affected differently by obstruction.

Rabbit urethra replacement with a defined biomatrix or small intestinal submucosa.

OBJECTIVE: The evaluation of collagen-based biomatrix (SIS COOK((R))) in comparison to a biochemically reconstructed biomatrix for replacement of the urethra in a rabbit model as a preclinical model. MATERIAL AND METHODS: Rabbits underwent partial urethra replacement (resection of 0.5 to 1.0 cm segment of the urethra), which was replaced with 1 or 4 layers Small Intestinal Submucosa (SIS COOK) patch grafts or with a biochemically defined collagen biomatrix, partly sutured with unresolvable sutures for future reference. Six animals underwent a sham control operation. The grafts of regenerated urethras were harvested at 1, 3 and 9 months after implantation. Urethrography was performed pre-operatively and before sacrificing. The animals were evaluated macroscopically and by routine histology and immunohistochemistry. RESULTS: At 1 month after implantation, the biomatrices (1 layer, 4 layers and our biochemically defined biomatrix) were well distinguishable from the normal surrounding tissues and showed blood vessels at the periphery. Macroscopically, the unresolvable reference sutures were easy to find at all time points. At 3 months the graft was still distinguishable in the 4 layers SIS group. In the 1 layer and the defined biomatrix group a good regeneration of the urethra within the graft was seen with some central fibrosis. Histological and immunohistochemical evaluation showed urothelium regeneration on the 1 layer and on biochemically defined biomatrix with decreasing number of inflammatory cells from 1 month on. In the group treated with 4 layers SIS the urothelium was completely regenerated at 3 months. Histologically, the regeneration of muscle cells in the three biomatrices was comparable. The smooth muscle cells regenerated very slowly as 1 month after implantation no muscle cells were detectable within the grafts. At 3 months a few muscle cells were present in the graft, but cell density did not increase in the following 6 months. Strictures were not observed on control urethrography pre-operatively in the animals. In one case slight narrowing of the urethra on urethrography was seen, but apparently without causing voiding problems. One rabbit developed a fistula near the operation site. CONCLUSION: The biomatrices investigated are feasible scaffolds to repair urethral lesions. The results with our biochemically defined biomatrix are comparable to one layer Small Intestinal Submucosa. Almost no smooth muscle cells population was observed after nine months for the three biomatrices. We conclude that an improved molecularly defined biomatrix focussed on stimulation of smooth muscle cell growth may be necessary to obtain optimal cellular grafting results.

Perinatal rupture of the uropoietic system.

AIMS: Ruptures of the uropoietic system resulting in either urinary ascites or urinoma are rare complications in the neonate. Although ruptures without clear predisposing factors are described, in most cases they are associated with obstructive uropathy. The diagnosis is often delayed and the prognosis is related to the degree of renal damage. There is discussion about possible protective mechanisms of the rupture for renal function in patients with obstructive uropathy. METHODS: We retrospectively analyzed the clinical presentation, predisposing factors and the renal function before and after treatment of 10 neonates with a rupture of the pyelum or urinary bladder in our hospital. RESULTS: The group consisted of 9 boys and 1 girl. The average birth weight was 3,880 g. The patients presented with distended abdomen (n = 10), abdominal mass (n = 2), ascites (n = 5), oligohydramnion (n = 2), hypertension (n = 1) and anuria (n = 1). Underlying diagnosis included obstruction of the ureteropelvic junction (UPJ obstruction) in 3 children and posterior urethral valves in 7 children. Five children presented with urinoma, 3 children had a urinoma in combination with ascites and 2 children had isolated ascites. All children had reduced renal function at the time of diagnosis. In all 10 cases, the serum creatinine decreased after treatment. Scintigraphic investigation with mercapto-acetyltriglycerine (MAG III) demonstrated diminished function and perfusion of all 3 kidneys with UPJ obstruction and isolated urinoma even after treatment. Children with posterior urethral valves and urinoma revealed better function of the ruptured kidney and diminished function of the kidney which was not ruptured. One child with a rupture of the urinary bladder and urinary ascites showed good function and perfusion of both kidneys. CONCLUSION: Perinatal ruptures of the uropoietic system are rare. The clinical presentation is aspecific. One should consider a rupture of the urinary bladder or pyelum in a neonate with a distended abdomen, hydronephrosis and ascites. The long-term prognosis depends on the underlying diagnosis and the location of the rupture. Probably, a UPJ obstruction with an isolated urinoma is associated with irreversible renal damage of the ruptured kidney. A rupture resulting in urinary ascites apparently provides better decompression with better function of the ruptured kidney. Scintigraphic investigation is necessary for a separate evaluation of the single kidney function.